I have a question about installing the rear radius rods. I have my differential put together and when I insert the radius rods in position and install the two bolts on the backing plate all is fine. When I look at the threaded end of the radius Rod by the u joint the end of the threads are flush with the collar. In other words, there aren't any threads sticking out to get the nut started on. Is the customary? I have a 1919 small drum differential. Are radius rods different lengths through the years?
Yes there are different lengths, 1908 to 1925 and 1926/27. Some clues in what you are describing, like collar and too short, you have the 1926/27 rods that are shorter. You need the earlier rods that used the double nut. To install those you will need to pull the drive shaft tube loose at the rear end. Did you take this rear end apart or putting it together from a pile of parts?
Mine are double nutted style and they came off the rear end in question but they were upside down (seam was up). When I eased off the front bolt the rods were under a lot of tension and when nuts came off threads the nuts popped off so to speak. I knew 26/27 differences but didn't know if earlier were different. I'll get a overall length
They measure (with tape on driveshaft side of rod) 57 1/4" from end of threaded Rod to center of bolt holes.
In a straight line from end of threads to approx mounting hole center I get just over 58 inches for the 25 and earlier rods. I would think that under that much tension your rear axle housings may be sprung. I would suggest checking them for straightness.
Mark thanks! That clears it up. I have a set of 26/27 rods. Yea!!! I get to search for yet another part
King, there is a noticeable difference at the back end of 26-7 radius rods. previous rods to fit small drum rear ends have legs on the Y section which are straight, just like the letter Y. On 26-7 the legs are spread wider initially and then they are bent in again within the legs, so the legs have an extra bend in them.
A photo would help, but I have no 26-7 samples.
Allan from down under.
In the past I have checked the nut tightening with a set up allowing a straight through end to end alignment of both ends and the center using only the radius rods to do it. I could get it within a few thousands. The one part I could not get was up---down of the center it took about ten pounds of push down to make it right---but if you allow half the weight of the torque tube and drive shaft ten pounds would have been very close to being within 10 thou all the way around.
Here are pictures of the ends of a 26-27 rear radius rod.
Now I have a question. I am trying to install the rods but they won't clear the rear axle to go into place. The drive shaft is already bolted up to the rear axle. Does it need to be loose to mount the radius rods?
Yes. Check the MTFCA rear axle book, the radius rods get installed the same time as the driveshaft. It can be done by one person, but it is much easier with a helper.
Thanks Mark. I've had the rear axle finished for some time now. Missed that part about the radius rods...
With the drive shaft housing installed in the rear axle the radius rod fork won't clear the rear axle by only a couple of milimeters. After loosening the spool they swing right into place. Need to reseal the spool with Permatex.
Not an improvement on the improved car.
Eric, I have always found that a little flexing will allow the radius rod to get past the axle housing at the rear, as long as you wind the nut at the front right back on the thread. A tap with a hammer will help stubborn ones. Of course, you will have a scratch in the paint to touch up.
Allan from down under.